title: Motor function in the elderly: evidence for the reserve hypothesis.
abstract: OBJECTIVE
  The reserve hypothesis accounts for the lack of direct relationship between brain pathology and its clinical manifestations. Research has mostly focused on cognition; our objective is to examine whether the reserve hypothesis applies to motor function. We investigated whether education, a marker of reserve, modifies the association between white matter lesions (WMLs), a marker of vascular brain damage, and maximum walking speed (WS), an objective measure of motor function. We also examined the cross-sectional and longitudinal association between education and WS.
  
  
  METHODS
  Data are from 4,010 participants aged 65-85 years in the longitudinal Three-City-Dijon Study with up to 4 WS measures over 10 years. We examined the interaction between education and WMLs for baseline WS. We studied the association between education and repeated WS measures using linear mixed models, and the role of covariates in explaining the education-WS association.
  
  
  RESULTS
  Education was strongly associated with baseline WS; the difference in mean WS between the high and low education groups (0.145 m/s, 95% confidence interval = 0.125-0.165) was equivalent to 7.4 years of age. WMLs were associated with slow WS only in the low education group (p interaction = 0.026). WS declined significantly over time (-0.194 m/s/10 years, 95% confidence interval = -0.206, -0.182), but education did not influence rate of decline. Anthropometric characteristics, parental education, general health, and cognition had the strongest role in explaining the baseline education-WS association.
  
  
  CONCLUSIONS
  Participants with more education were less susceptible to WMLs' effect on motor function. Higher education was associated with better motor performances but not with motor decline. These results are consistent with the passive reserve hypothesis.
authors.affiliation: INSERM, Centre for Research in Epidemiology and Population Health, U1018 Social and Occupational Determinants of Health, Villejuif, France. alexis.elbaz@inserm.fr
authors.forename: Alexis
authors.initials: A
authors.lastname: Elbaz
authors.forename: Pavla
authors.initials: P
authors.lastname: Vicente-Vytopilova
authors.forename: Béatrice
authors.initials: B
authors.lastname: Tavernier
authors.forename: Séverine
authors.initials: S
authors.lastname: Sabia
authors.forename: Julien
authors.initials: J
authors.lastname: Dumurgier
authors.forename: Bernard
authors.initials: B
authors.lastname: Mazoyer
authors.forename: Archana
authors.initials: A
authors.lastname: Singh-Manoux
authors.forename: Christophe
authors.initials: C
authors.lastname: Tzourio
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000473:pathology* / Q000502:physiology*; D058245:Cognitive Reserve / Q000502:physiology*; D015331:Cohort Studies; D004522:Educational Status; D005260:Female; D005602:France / Q000453:epidemiology; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D009048:Motor Skills / Q000502:physiology*; D009413:Nerve Fibers, Myelinated / Q000473:pathology; D016138:Walking / Q000502:physiology